ISDN is also known as Integrated Services Digital Network. It is helpful in a wide range of services, for example, text (message), image, etc. It is capable of giving services and the foundation of telecommunication networks i.e. useful in the framework.
It was also known as Integrated Digital Network because it is a digital technique that is used in switching as well as in transmission.
It has three types of Channel.
Data-rate: 64 kbps.
Required: for voice, information which has less data rate.
Data-rate: 16-64 kbps.
Required: for packet switched data.
Data-rate − 1536 kbps or 1920 kbps data rate.
Required − for video/ high-speed data or audio, etc.
The following are the types of layers −
ISDN has four types of interfaces or services, which are as follows −
Basic Rate Interface (BRI) − BRI uses the current infrastructure of telephone. It provides configuration for B-channel at the data rate of 64 kbps and D-channel at the data-rate of 16 kbps.
Primary Rate Interface (PRI) − PRI uses T-carriers in the United States and E-carrier in Europe.
Narrowband ISDN − It acts as a carrier of voice information by using less bandwidth.
Broadband ISDN − It helps in transmission of media by using high bandwidth as compared to narrowband ISDN.